1. Field of the Invention
The present invention relates to devices for efficient transport, transfer and movement of fluids. In particular, the invention provides fluidic micro-structures for controlled transport and movement of liquids in devices for analytical and other purposes. Devices of the invention include one or more features that can enhance performance of the fluid transfer, described below and referred to as a xe2x80x9cpre-shooter stopxe2x80x9d, a xe2x80x9cbutterflyxe2x80x9d structure, a xe2x80x9ccascadexe2x80x9d structure, a waste chamber inlet, a capillary driven sample inlet chamber, a capillary stop structure, a bifurcation flow-through mechanism, and a hydrophobic vent.
2. Background
The development of bio-array technologies promises to revolutionize the way biological research is carried out. Bio-arrays, wherein a library of biomolecules is immobilized on a small slide or chip, allow hundreds to thousands of assays to be carried out simultaneously on a miniaturized scale. This permits researchers to quickly gain large amounts of information from a single sample. In many cases, bio-array type analysis would be impossible using traditional biological techniques due to the rarity of the sample being tested and the time and expense necessary to carry out large-scale analysis.
Bio-arrays or chips as substrate platforms for analytical purposes will continue to transform the way the analysis and the determination of materials will be carried out in the future. Low cost chips will become established in a variety of fields where easy and rapid analysis is demanded with very low amount of sample availability. For example, such fields may include: medical, clinical, biochemical, chemical, environmental, food, and industrial analysis. In many of these areas, analysis is limited or even impossible using traditional laboratory techniques due to the very time-consuming and expensive procedures, combined with high sample volume requirement.
Although bio-arrays are powerful research tools, they suffer from a number of shortcomings. For example, bio-arrays tend to be expensive to produce due to difficulties involved in reproducibly manufacturing high quality arrays. Also, bio-array techniques cannot always provide the sensitivity nor the consistent results necessary to perform desired experimentation. Therefore, it would be desirable to provide an improved device which is available for a variety of miniaturized analytical purposes including analytical chips, and allowing for effective transport, delivery, and removal of liquids for efficient experimentation using bio-arrays.
The present invention provides novel fluidic devices for efficient transport of fluids. Devices of the invention are suitably employed for analytical studies and other applications using bio-arrays or microchips.
Devices of the invention include one or more features that can enhance performance of fluid transfer through the device structure, such features are generally referred to herein as a pre-shooter stop, a butterfly structure, a cascade structure, a waste chamber inlet, a capillary driven sample inlet chamber, a capillary stop structure, a bifurcation flow-through mechanism or structure, and a hydrophobic vent.
Preferred devices of the invention, including microstructured devices useful for analytical purposes can comprise a filling station or section, an analysis station or section and a waste station or section. Generally preferred devices according to the invention include one or more features that can enhance performance of fluid transfer through the device structure, such features generally referred to herein as a sample inlet chamber (e.g. a capillary drive sample inlet chamber), a butterfly structure, a bifurcation flow-through structure, a cascade structure, a pre-shooter stop structure, a capillary stop structure (e.g. a flow-gate, optionally with evaporation stop), a vent (e.g. a hydrophobic vent), a waste outlet, a waste collecting chamber, and a waste inlet into a waste collecting chamber.
The filling section can comprise an inlet port, an inlet channel, a filling chamber and an outlet channel. The inlet channel connects the inlet port to one end of the filling chamber, the volume of which is preferably sufficiently large to take up the entire volume, or essentially entire (e.g. at least about 95 vol %) of a fluid sample. The outlet channel connects preferably the other end of the filling chamber (opposite to the inlet channel) top the analysis section.
The analysis section can comprise a channel, the entrance of which is connected to the filling section. The volume of the channel of the analysis section is suitably less than the volume of the filling chamber. The cross-section, the length and the shape of the channel located in the analysis section are adapted to the intended use of the device.
The waste section comprises at least an outlet for the fluid leaving the analysis section. The waste section can comprise further a waste chamber for collecting fluid coming out of the analysis section, and a connecting channel between the exit of the analysis section and the waste collecting chamber.
The filling section, the analysis section and the waste section can comprise various structures for the precisely controlled transport of fluids through said sections.
In further detail, a pre-shooter stop of devices of the invention can inhibit undesired edge fluid flow, i.e. where an introduced fluid flows through the device more quickly along the flow channel edges than the middle regions of the flow channel. The pre-shooter stop includes irregularly-shaped edges of the flow channel, particularly triangular or saw-toothed edges that allow for an even advancing flow line through a flow channel.
The butterfly and cascade structures of devices of the invention can provide a more homogeneous spread of a fluid stream that enters a relatively wider flow area from a narrower flow area. The butterfly structure as referred to herein is a symmetrical V-shaped or delta-shaped pair of flow channels that emerge from a single flow channel. The two channels have the same cross-sectional area as the single channel that flows or feeds fluid into the two channels. The two channels present a common V-shaped front to the single channel that feeds fluid into the channels.
The cascade structure as referred to herein includes a triangular shaped structure with steps (terraces) of increasing depth in the direction of the triangle top, thereby providing a decreased capillary force. That structure can provide for flowing fluid to fill out each level or step before flowing to a next level, again promoting a homogeneous spread of fluid.
A device of the invention also can include a certain fluid inlet coupled to a waste structure that receives spent test sample, wash fluids, etc. The waste chamber inlet contains an inlet neck that is graded with notches that can contact and adhere to fluid absorbent material such as fleece contained within the waste chamber.
A device of the invention also may contain a fluid receiving chamber that promotes capillary flow of the fluid through the device. The receiving chamber suitably can be e.g. a vertical wedged-shape slot, with decreasing width into the device, or a funnel-shaped inlet with decreasing diameter into the device. Fluid can be pipetted or otherwise introduced into the receiving chamber and thereby flow via capillary forces through the device.
A device of the invention may further contain a capillary stop, which can provide for capillary fluid flow to be substantially interrupted at a defined point. A capillary stop includes a flow channel or space of low capillarity at the end of a flow channel or space of high capillarity, or a flow channel or space of low capillarity between two channels of high capillarity. Fluid will stop at the end of the channel of high capillarity and will not enter the flow space of low capillarity.
A device of the invention may further contain an air exit vent that is capped by a hydrophobic, air permeable material. The material may suitably be a hydrophobic polymer frit or a polymer membrane. Such a cap enables air to exit from the device, as well as air to degass from the fluid, as fluid fills the device. The cap can also serve as a stop for the fluid upon filling of the device flow path(s); and as a marker for filling of the device with fluid.
Fluidic devices of the invention are xe2x80x9cclosedxe2x80x9d systems, i.e. where fluid flows into an encased compartment. As discussed above, the device provides ports for introduction of liquid into the container and venting of air out of the container. The ports connect to a fluid flow system, which preferably can operate by capillary forces. The device also may contain an outlet port, suitably coupled with a waste chamber within the container, provided for expelling and containing waste materials.
Function and effect of the filling section are suitably provided as follows. The predetermined volume of the fluid sample is introduced into the inlet port e.g. by use of a pipette. The tip of the pipette can be tightly pressed into the funnel-shaped inlet port. The fluid enters the connecting channel from the inlet port to the filling chamber, if necessary by applying some pressure onto the fluid in the pipette. Upon filling of the filling chamber with fluid, the pipette can be withdrawn.
During filling of the filling chamber and subsequently filling of the analysis section and optionally partially filling of the waste section, air is suitably vented from the channels and hollow spaces through the vent.
The filling section allows the well-defined filling of the analysis section by capillary forces alone or by applying external forces. The arrangement of the filling section allows filling of the analysis section completely without bubbles independently from the skill of the operator.
The volume of the filling chamber suitably can vary widely depending on device design, e.g. from about 1 microliter to about 1000 (one thousand) microliter, more typically from about 1 microliter to about 500 microliter, still more typically from about 1 microliter to about 100 microliters.
Function and effect of the analysis section are suitably provided as follows. The analysis section comprises essentially a closed channel having a given length and a cross-section and shape of cross-section. A variety of designs are suitable, e.g. a straight hollow chamber or a curved shaped chamber. The exit of the analysis section can be connected to further fluidic structures. The hollow space of the analysis section can be filled by capillary forces and/or additionally by active flow propulsion depending on the ratio of chamber width to chamber length and on characteristics of the fluid.
Within the hollow space of the analysis section e.g. chemical reactions or bio-reactions or hybridization or other effects can take place resulting in an alteration of preferably optical properties of the fluid contained in the analysis section. Such properties can be detected by known optical methods.
The waste section is determined for removing fluid coming out of the analysis section and preferably for collecting such fluid in a waste chamber.
Devices of the invention may have one or more preferably more than one or all of the above-discussed features, i.e. a pre-shooter stop, a butterfly structure, filling section, analysis section, a cascade structure, a waste chamber inlet, a capillary driven sample inlet chamber, a capillary stop structure, a bifurcation flow-through mechanism, and a hydrophobic vent, and other features mentioned herein.
Devices of the invention are suitably used for applications or assays which include biomolecules introduced into the device, including nucleic acids, peptides, and the like.